The present invention related to dental equipment, and more particularly, to teaching tools for the use of endodontic apical location equipment.
Precise location of the root apex is vitally important for the correct endodontic treatment of a tooth. If the endodontic procedure of extracting and cleaning the pulp tissue from a root canal is performed at a length short of the apex, pulp tissue may remain in the canal. Failure to remove all pulp tissue may lead to infection and pain for the patient and necessitate additional surgery. If the endodontic procedure is performed beyond the length of the root apex, the reamer may penetrate into the periodontal ligament leading to pain and extreme sensitivity to the patient.
Multiple methods are currently utilized to determine the location of the apex during an endodontic procedure on a live patient. One is the use of x-ray radiographs of the tooth while a metal endodontic reamer is located in the root canal. This allows the dentist to visually compare the length of the metal reamer to the location of the end of the root to determine the location of the root apex. This method may be unreliable and not cost-effective.
A second method is to use an electrically aided apical position location. Electrical aid approaches include those described in U. S. Pat. No. 5,759,159 to Masreliez, U.S. Pat. No. 5,211,556 to Kobayashi et al, and U.S. Pat. No. 6,059,569 to Otsuka, all incorporated herein by reference. These patents describe apical position locators utilizing impedance measurements to determine the location of the root apex. In the electrical approach, an electrically-conductive probe is inserted into the root canal and a second electrode is attached to the patient""s body, such as by hanging a hook shaped electrode from the patient""s mouth. As the probe is inserted into the root canal and advanced through the root canal to the root apex, the impedance is measured. Once the impedance reaches a determined range or value, the location of the apex is indicated. The electrical approach for determining apex location is currently the standard technique used in endodontic practice and taught in dental schools.
Instruction in the use of electrical apical position locators has generally required practice upon live patients in need of endodontic treatment. Performing endodontic procedures on healthy teeth is unethical and represents dental malpractice. Endodontic patients are often in pain prior to seeing the dentist, and are usually apprehensive about the endodontic procedure and less than enthusiastic about serving as subjects in dental instruction on the use of apical position locators. The additional pain which may be encountered, or the mere potential for such additional pain, is an effective disincentive to enthusiastic participation.
The number of endodontic procedures that a graduate student in endodontics or a doctoral student in general dentistry performs on live patients is severely limited by the number of willing participants in need of such procedures. Graduate endodontists and general dentists would benefit from additional training and instruction in the use of apical position locators in a realistic setting. In turn, the endodontic patient would benefit from the additional training received by the practitioner.
Prior to this invention, no adequate surrogate for the live patient has been developed for instruction in the use of electrical apical position locators. U.S. Pat. No. 5,503,562 describes a transparent endodontic inspection block which allows the endodontist or endodontic student to simulate cleaning out the root canal. The student utilizing the inspection block could look through the side of the inspection block and locate the root apex. This invention is not designed to train apex location techniques and does not represent realistic conditions of endodontic treatment. U.S. Pat. No. 4,137,633, issued in 1979, disclosed a resilient mass located at the apex of a block of transparent material to simulate the tactile sensation of the periodontal membrane located at the apex of a natural tooth. Thus, prior devices permitted students to visually locate a simulated apex through a transparent block and to tactually locate a simulated apex through the addition of a resilient mass located at the apex. No known prior devices have disclosed providing a simulation of a live tooth and human tissue to practice using an electrical apical position locator.
The present invention provides an improved device and method for the training of the use of an apical position locator. The invention uses a real or replicated tooth with a root and a root canal having an apex generally coincident with the root tip. The inventor""s concept is to provide a medium into which the tooth is set which mimics the electrical impedance of human tissue so that an electronic apical locator may be used. In a first embodiment, and the broadest concept of the invention, the tooth is mounted in a single, rigid conductive medium which mimics the conductivity characteristics of human tissue. An alternative embodiment uses a first highly conductive medium wrapped around the root tip to cover the apex and the tooth and first conductive medium is then set in a fixture containing a rigid, second less conductive medium which holds the tooth suitably for manipulation training purposes. An electronic apical position locator has one lead connected to an endodontic reamer and the other to an electrode blade extending from the medium. When the reamer is inserted in the root canal and extended so that the reamer tip contacts the conductive medium at the canal apex, the electronic circuit of the apical position locator is closed, the impedance is measured and the apex is appropriately indicated by the apical position locator. A more detailed understanding of the invention will be obtained from the following description of the preferred embodiments taken in conjunction with the attached drawings.
This invention utilizes an actual or replicated human tooth with an electrically equivalent replicated human tissue medium to provide a realistic simulator for training in the use of an electrical apical position locator. Patient volunteers do not normally clamor for dentists-in-training to practice root canals upon them, so this invention allows the endodontic student the opportunity to practice in a realistic environment. The user may select a partially radiopaque electrically conductive medium, which allows the student to also simulate the determination of the location of the root apex through the use of an x-ray radiograph.